1. Field of the Invention
This invention relates to an electrostatically aided filter apparatus through which gaseous fluid carrying dust or other particulate matter is directed in order that it may retain the particulate matter while the clean gas is permitted to flow continuously therethrough.
2. Description of the Prior Art
According to U.S. Pat. No. 3,733,784, particulate matter approaching a filter means is subjected to an electric charge while a metallic support cage for a filter bag is subjected to a similar charge that causes the charged particles to be repulsed therefrom. A housing that surrounds the filter means is given an opposite charge (grounded) so that the charged particles are attracted thereto instead of collecting upon the filter itself. Therefore, some particulate matter collects upon the housing and other particulate matter is collected upon the surface of the filter.
As dust laden gas enters the filter housing, some of the charged particulate matter collects on the oppositely charged housing wall while other particulate matter collects on the filter itself. Inasmuch as the filter is supported on a mesh of widely spaced conductors that carry a charge similar to that originally given the particulate matter, all particulate matter should be repulsed therefrom. However, due to the fact that the wires of the wire cage supporting the bag filter are widely spaced, the strength of the electric field between said wires is low and there is practically no electrostatic repulsion of dust particles. Therefore the particles collect, compact, and then resist the passage of more fluid.
The present invention imparts to the particulate matter entering a filter apparatus a given electrostatic charge, but it does not give an opposite charge to the surrounding housing so the particulate matter is not attracted thereto. Instead, "like" charges are imparted to the particulate matter entering a filter housing and to a finely divided porous support for filter means therefor whereby all the particulate matter will collect loosely on the filter to provide a finely dispersed filter body that enhances further filtration. This is essentially true because all of the individual particles being collected on the filter have the same charge as the porous base and as each other, so collectively they comprise a loosely held particle mass.